’98 BMW Z3M Coupe

’98 BMW Z3M Coupe

Early 2018 we’ve got asked to rebuild this 1998 Z3M Coupe. It had been in storage for over 3,5 years and the owner wanted to wanted the have the S50 drivetrain in tip top condition before start to using it again. Together with the customer we made a list of “to-do’s” based on our recommendations, customer experience and the service history. Some highlight’s from the long task list included: Complete Vanos overhaul, Throttle body service and synchronization, injector service, new engine mounts, new clutch and flywheel, shifter mechanism rebuild, Vacuum system overhaul, new wishbones, and many more. Off course we also give the car a extensive wash and polish.

We’ve started with the collection of the car in Belgium.


Afbeelding

Afbeelding.
Afbeelding

Back in the workshop we first took our time to admire the car. In our opinion one of the most special BMW’s ever made. 
Afbeelding

Afbeelding

Time to start the wrenching on the car. We begin with a compression test to see how the condition of the S50 is after 200.000 km.
Afbeelding


Afbeelding

Afbeelding

Afbeelding

All okay, so we can start with the disable of the engine components that need service.Afbeelding

The Throttle bodies are quite dirty, so a lot of improvement to gain!
Afbeelding

Afbeelding

The valvetrain cover removed. Very clean, especially after 200.000 km!Afbeelding


Afbeelding

Next step is to rebuild the VANOS. The famous “vanos rattle” was clearly audible and the customer noticed it was lacking torque.Afbeelding


Afbeelding

The VANOS unit of the S54 is in principle the same as the more commonly known S54 vanos unit, but has a few differences, which gives a nice in-sight how the BMW engineer’s optimized the design of the S54 vanos unit from the S50 unit.

The condition of the vanos unit was very poor. We could easily rock the Camshaft, so the VANOS was definitively in need of a rebuild!

Afbeelding

The vanos unit removed;
Afbeelding

The vanos unit could definitely use a cleaning! The seals of the solenoids often break (like all other seals of this vanos) and starts to leak. The leaking seals are replaced by S62 trapezium shaped solenoid seals, which seal much better.

Afbeelding

Afbeelding

Meanwhile, to ITB’s are removed and ready to be cleaned and polished. There has a been a lot of dirt build up over de years, so a service is well worth the effort.
Afbeelding

Afbeelding

Afbeelding

Afbeelding

After the cleaning;
Afbeelding

Afbeelding

Afbeelding

Afbeelding

The airbox and inlet components get a good cleaning as well. At first sight they don’t look that different, but once you start cleaning them, a lot of debris comes out.Afbeelding

As the customer complained about a “loose” clutch pedal, we replaced the clutch pedal bushings with a bronze “upgraded” versions. A huge difference compared to the worn about plastic version.


Afbeelding

Afbeelding

Now all parts are disassembled, it is time to start the reassembly. We begin with the VANOS;Afbeelding

Afbeelding

Two O-Rings were completely gone. No wonder the VANOS didn’t work properly and was leaking…

Afbeelding

Afbeelding

Afbeelding

Afbeelding

We “opperate” the VANOS in order to properly clean them;

Afbeelding

Two bolts of the solenoid cover were broken. Luckily we were able to remove the broken bolts without much trouble;Afbeelding

Before we could install the new seals, we conducted a lot of cleaning work. To illustrate the dramatic difference before and after, before and after;

Before:

Afbeelding

After:
Afbeelding

Afbeelding

Afbeelding

Afbeelding

Meanwhile, we proceeded with loosening the hubs so we could install stronger diaphragm springs (S62), quite a job with the S50 because the exhaust camshaft has to be completely removed in order to have enough room to remove the hub. The diaphragm springs were so weak that the splined shaft of the inlet camshaft could be pulled out by hand…

We noticed a lot a dirt below the VANOS unit, caused by the leaking VANOS unit. Off course we had to clean this before we could proceed!Afbeelding

Afbeelding

Much better;
Afbeelding

Intake hub can be removed with camshaft installed;

Afbeelding

After disassembly of the intake camshaft, the exhaust side hub can be removed as well.Afbeelding

The old (S50) and new (s62) springs next to each other. It is clear to see that the S50 springs worn.
Afbeelding

Also, they are significant thicker;
Afbeelding

We measured the axial play on the splined shafts. Not that bad, but worth the effort of installing an “anti-rattlekit”.
Afbeelding

The axles of the splined shaft removed in order to be able to installed the new anti-rattle kit. This should be precisely shimmed out, which means a few loops of installing, measuring and disassembling again.
Afbeelding

A few overview photo’s of the VANOS subcomponents;

Afbeelding

Afbeelding

Afbeelding

E

Time to reassemble the VANOS. First we installed the hubs with the S62 springs;


Afbeelding

Vanos control unit stalled with laser engraved service label;Afbeelding

Now that the timing is secured again, we are able to rotate the engine. A good moment to check the valve clearance, which didn’t require any adjustment;

Afbeelding

While we’re add it, it is worth documenting which shims are used so a next “adjustment” can be done much quicker;


Afbeelding

The throttle bodies are ready to be reinstalled;
Afbeelding

To be able to properly synchronize them, we designed our “sync tool” for the S50 as well and printed them on our 3D printer;

Afbeelding

We’ve set the throttle bodies to make sure to open and close at exactly the same time;Afbeelding

Next step is to conduct and injector check and service on our injector testbench. We check the injectors for leak, spray pattern and flow.Afbeelding

Beside the steps describes above, we also cleaned and replaced a large part of the vacuum system and crankcase ventilation system. Absolutely well worth it as many little hose we’re already leaking or almost leaking. It is not interesting to show all the hose, but a good example of the condition of the hoses;


Afbeelding

We’re getting close to closing the engine again, so it is time to replace the engine oil. We fill the first liters will the engine is still open, so engine is already divided when the engine starts to rotate.Afbeelding

Together with the customer, decided is to use  Motul 300V Chrono 10w40;Afbeelding

Offcourse we close the engine with a cleaned valve cover;


Afbeelding

Reinstallation of the spark plugs;Afbeelding

Detailing

The engine is closed, so we can give the engine bay a thorough cleaning;Afbeelding

Afbeelding

Afbeelding

Afbeelding

Next up was the exterior. Although the car looks already shine on the photos, in real life there was definitely improvement to be made;

Afbeelding

Afbeelding

We’ve started by claying the complete car, well worth the effort;Afbeelding

Afbeelding

A quick “50/50” shot which shows the difference before and after the polish;Afbeelding

End result:

Afbeelding

Afbeelding

Afbeelding

The trained eye already noticed the Z3M had the wrong M-logo on the back. We replaced the newer (s54 logo) with the correct (s50) logo. Off course we took our time to place the logo on exactly the right position;Afbeelding

Afbeelding

Tranmission

Afbeelding
We’ve moved to underneath the car to replace the flywheel, clutch and shifter mechanism. First a overview of the parts;

Afbeelding

Afbeelding

Afbeelding

Started with removing the exhaust, which was a real struggle to get off;Afbeelding

Upon closer inspection we notice a ripped transmission mount. Not good;Afbeelding

Afbeelding

Transmission removed. Obviously dirty after 200.000 km, but otherwise appears to be in good condition;Afbeelding

Afbeelding

Afbeelding

Fast forward after a “bit” of cleaning;Afbeelding

Afbeelding

While we are at it, it is definitely worth replacing the shifter mechanism;

Afbeelding

Afbeelding

The old clutch and flywheel removed, new components ready to be installed. The old dual mass flywheel had a significant amount of play, so good to replace;Afbeelding

With the flywheel removed, we took the opportunity to replace the crankshaft seal and top bearing;Afbeelding

New parts installed;Afbeelding

 

The broken transmission mount did cause some damage to the car. Fractures on all 4 mounting points;
Afbeelding

We began by drilling small holes at the end of all fractures. It is important to do this before removing the bodycoating, as the grinding marks might disguise the true beginning and ending of the crack. Once the hole was drilled, we carefully removed the paint/bodyspray;


Afbeelding

Afbeelding

Next step is to carefully “grind’ a groove in the crack, so it easy to make a good penetrated weld. We installed a long bolt in the hole, to check for alignment and adjust when required;Afbeelding

After welding and grinding, there is no sign of the crack to be seen anymore;
Afbeelding

Meanwhile we bought a new transmission mount, with new mounting rubbers;

Afbeelding

After protecting the welds and bear metal against rust, we could install the gearbox and new mount. Very satisfying when everything is as it should again;Afbeelding

Afbeelding

With the transmission done, we moved to the front of the car to replace the wishbones and rubbers. Most difficult part of this job was to get OEM wishbones, as there were in backorder at BMW and the dealer was not able to give a date when they would be available. We managed to purchase the LHS wishbone in Germany and the RHS in France;


Afbeelding

The rubbers were still the original once from ’98;


Afbeelding

While underneath the car, we conducted some standard service work like a brake fluid change, clutch fluid change, differential fluid change and repaired an steering fluid leak. The oil leaks from the engine and steering fluid covered the hole underside of the engine in a grease and dirt. With the leaks fixed, we cleaned all old debris off to make sure with a next service job a starting leak can easily be spotted and tracked down. An example of some cleaning;


Afbeelding

Afbeelding

The work on the car is done, so it time to take it out to start it up and take some photos:
Afbeelding

Afbeelding

Afbeelding

Afbeelding

Afbeelding

Afbeelding

Afbeelding

Last check for fault codes;Afbeelding

Ready to deliver!
Afbeelding

Afbeelding

Afbeelding

One Response

  1. Niels says:

    Geweldig! Imola is eigenlijk het mooist imho.

Leave a Reply

Your email address will not be published. Required fields are marked *